Author Topic: 028S - worn piston  (Read 313 times)

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Offline jmester

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Re: 028S - worn piston
« Reply #10 on: November 13, 2016, 07:17:57 am »
Check your gmail. I don't have one for the 029. The one that I sent is for the MS 290-390. It will work just fine. There is only some minor differences from the 0 model to the ms model 029-290. Hope it helps, don't hesitate to ask questions as that is why we all come together to help each other. Looks like it had a lean running condition based off the scoring on the exhaust side of the piston. Could be caused from many things lean carb setting,crankcase air leak are some of the more common ones.
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Offline qigley

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Re: 028S - worn piston
« Reply #11 on: November 13, 2016, 10:15:43 pm »
I can send you the manual to your gmail as long as you updated your profile page here. Also based on the pic looks like you have a 029 super. A clamshell engine design.
Thanks I got it. And is an 028 Super, as per the decals attached to it.

The one that I sent is for the MS 290-390. It will work just fine. There is only some minor differences from the 0 model to the ms model 029-290. Hope it helps, don't hesitate to ask questions as that is why we all come together to help each other. Looks like it had a lean running condition based off the scoring on the exhaust side of the piston. Could be caused from many things lean carb setting,crankcase air leak are some of the more common ones.
Thanks. Does the fact it is an 028 super change anything in the statement you made about its relevance to that service manual?

Offline Cut4fun .

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Re: 028S - worn piston
« Reply #12 on: November 14, 2016, 12:03:01 pm »
This saw in pic isnt a 028 super. 

Like jmester said. Looks like 029 or 029 super

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Offline Cut4fun .

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Re: 028S - worn piston
« Reply #13 on: November 14, 2016, 12:08:06 pm »
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Offline oldpro

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Re: 028S - worn piston
« Reply #14 on: November 14, 2016, 03:11:12 pm »
From the photo the piston is fried,the cyl. won't look too good either,but you can try to save it if you want..

Offline qigley

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Re: 028S - worn piston
« Reply #15 on: November 14, 2016, 07:38:33 pm »
This saw in pic isnt a 028 super.  Like jmester said. Looks like 029 or 029 super
Yep, you guys are right, that wasnt my saw in the pic I put up on Pg 1.  I downloaded that pic off the net some time ago, and forgot, and now wrongly assumed  that it was a pic I took of my problem.

My saw is definitely a 28S, and of course looks exactly like it does in the link I was given.I tried to take a pic of the piston, but my camera cant focus properly.  What I see thru the exhaust port is some hard scuffing just below the rings for 1/5 of an inch or so, then the remainder of the skirt is clean and shiny below that and not scuffed at all.

Anyways I was wondering more than the fault itself, whether there were other diagnostic checks I should do, such as crank seals, etc?  Since the 28 is not a clamshell motor, it is  a simple service  to just pull off the cylinder. So Im thinking of just doing that, replace the cyl + piston if needs be, and re use and go from there and see whether its useable as is.  The carb has been rebuilt, so if the cyl/piston rebuild doesnt make it run good, then all I have left to do is get in to the crank area.

False strategy or not?

Offline jmester

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Re: 028S - worn piston
« Reply #16 on: November 14, 2016, 09:45:57 pm »
Maybe just carbon smear or the beginning of a lean run condition. Before you tear it down any more I would check the crankcase for air leaks. This is done by a pressure and vacuum test. Then go from there. I will send the 028 service manual to your gmail. I will send you a Stihl engine fault manual as well maybe there is a pic in the manual that looks like what you have going on then I can better help.
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Offline jmester

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Re: 028S - worn piston
« Reply #17 on: November 14, 2016, 09:57:55 pm »
Manuals and IPL should be in your gmail. Hope it helps.
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Offline qigley

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Re: 028S - worn piston
« Reply #18 on: November 14, 2016, 10:55:39 pm »
Yep I got all all thanks a lot for that, that will help a noob like me heaps. Much appreciated.

Offline oldpro

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Re: 028S - worn piston
« Reply #19 on: November 23, 2016, 10:54:26 pm »
That piston is cooked! but being an older saw it probably has chrome plating,which means there is a chance to save the cyl.

 

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